本文關(guān)鍵詞：延遲容忍網(wǎng)絡(luò)中路由算法的研究　出處：《電子科技大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 延遲容忍網(wǎng)絡(luò) 路由算法 條件接觸間隔時(shí)間 接觸持續(xù)時(shí)間

【摘要】：隨著科技的進(jìn)步,具有無線接口的通信設(shè)備越來越普及。在這個(gè)過程中出現(xiàn)一種特殊的無線移動(dòng)網(wǎng)絡(luò)——延遲容忍網(wǎng)絡(luò)(Delay Tolerant Network,DTN)。與傳統(tǒng)的無線網(wǎng)絡(luò)不同,DTN不存在持續(xù)的網(wǎng)絡(luò)連接并具有節(jié)點(diǎn)頻繁移動(dòng)、資源受限等特點(diǎn)。由于DTN的這些特性,DTN的路由變得非常具有挑戰(zhàn)性,因?yàn)樗仨毺幚砭W(wǎng)絡(luò)中存在的網(wǎng)絡(luò)劃分、長(zhǎng)延時(shí)和節(jié)點(diǎn)動(dòng)態(tài)拓?fù)涞葐栴}。DTN最初被用于星際網(wǎng)絡(luò),目前存在多種不同的應(yīng)用場(chǎng)景,包括無線傳感器網(wǎng)絡(luò)、軍事自組織網(wǎng)絡(luò)、車載網(wǎng)絡(luò)和社交網(wǎng)絡(luò)等等。在DTN中,不可能存在從源端到目的端的持續(xù)網(wǎng)絡(luò)連接。因此,在DTN中,消息的傳輸依賴機(jī)會(huì)路由,其中節(jié)點(diǎn)使用存儲(chǔ)-攜帶-轉(zhuǎn)發(fā)的模式來進(jìn)行消息路由。然而,基于有限的歷史接觸信息來制定有效的轉(zhuǎn)發(fā)策略仍然是具有挑戰(zhàn)性的。本文首先研究了DTN中已存在的一種依據(jù)歷史相遇和傳輸信息的概率路由算法(Probabilistic Routing Protocol using History of Encounters and Transitivity,Prophet)。然后引入了一種附加測(cè)度——條件接觸間隔時(shí)間,這一測(cè)度只使用本地的歷史相遇信息來計(jì)算兩個(gè)節(jié)點(diǎn)相對(duì)于第三個(gè)節(jié)點(diǎn)的相遇之間的平均接觸間隔時(shí)間。我們還分析了引入的附加測(cè)度并說明了它在路由中的重要性。接著引入接觸持續(xù)時(shí)間的概念,并分析其合理性。最后本文利用接觸持續(xù)時(shí)間和條件接觸間隔時(shí)間分別對(duì)Prophet的概率計(jì)算和轉(zhuǎn)發(fā)策略進(jìn)行了改進(jìn)。實(shí)驗(yàn)結(jié)果表明,改進(jìn)后的Prophet有效地降低了延時(shí),提高了消息的投遞率,減少了網(wǎng)絡(luò)開銷。然后在改進(jìn)后的Prophet基礎(chǔ)上,分析了散發(fā)與等待(Spray and Wait,SW)路由算法在散發(fā)階段和等待階段的不足,提出了一種改進(jìn)的基于概率的散發(fā)與等待路由算法。在原有的散發(fā)與等待路由算法的散發(fā)階段中,節(jié)點(diǎn)盲目地將消息副本散發(fā)給所有與它相遇的節(jié)點(diǎn)�；谶@一點(diǎn),本文對(duì)散發(fā)與等待路由算法的散發(fā)策略進(jìn)行改進(jìn)�？紤]節(jié)點(diǎn)的所有鄰居節(jié)點(diǎn)的消息遞交概率值,應(yīng)用公式計(jì)算出散發(fā)給各節(jié)點(diǎn)的消息副本數(shù)。另外在等待階段,攜帶消息副本的節(jié)點(diǎn)不再是等待目的節(jié)點(diǎn)然后直接交付。當(dāng)節(jié)點(diǎn)在移動(dòng)的過程中遇到與目的節(jié)點(diǎn)相遇概率更大且條件接觸間隔時(shí)間更小的節(jié)點(diǎn)的時(shí)候,將消息副本將轉(zhuǎn)發(fā)給該節(jié)點(diǎn)。仿真結(jié)果表明,改進(jìn)后的路由算法在消息的遞交成功率、平均端到端時(shí)延、網(wǎng)絡(luò)開銷等方面有良好的性能。
[Abstract]:With the progress of science and technology, the communication equipment with wireless interface is becoming more and more popular. In this process, there is a special wireless mobile network, the Delay Tolerant Network (DTN). Unlike traditional wireless networks, DTN does not have a continuous network connection and has the characteristics of frequent mobile nodes and limited resources. Because of these characteristics of DTN, routing of DTN is very challenging, because it must deal with network partition, long delay and node dynamic topology. DTN was originally applied to interplanetary network. There are many different application scenarios at present, including wireless sensor network, military self organizing network, vehicular network and social network. In DTN, it is not possible to have a continuous network connection from the source to the destination. Therefore, in DTN, the transmission of messages depends on the opportunity routing, where the nodes use the storage - carry - forward mode for message routing. However, it is still challenging to make effective forwarding strategies based on limited historical contact information. In this paper, we first study a Probabilistic Routing Protocol using History of Encounters and Transitivity, which exists in DTN, which is based on historical encounter and transmission information. Then an additional measure -- the conditional contact interval time is introduced. The measure only uses the local historical encounter information to calculate the average contact interval between two nodes relative to the third nodes. We also analyzed the additional measure introduced and explained its importance in routing. Then the concept of contact duration is introduced and its rationality is analyzed. At last, the probability calculation and forwarding strategy of Prophet are improved by using contact duration and conditional contact interval time respectively. The experimental results show that the improved Prophet effectively reduces the delay, improves the delivery rate of the message, and reduces the network overhead. Then, on the basis of the improved Prophet, we analyze the shortcomings of the Spray and Wait (SW) routing algorithm in the sporadic stage and the waiting stage, and propose an improved probabilistic based distributed and wait routing algorithm. In the emanating phase of the original emission and waiting routing algorithm, nodes blindly distribute the copy of the message to all the nodes that meet it. Based on this, this paper improves the emission strategy of the emission and waiting routing algorithms. The number of messages sent to each node is calculated by using the application formula to calculate the probability value of the message submitted by all the neighbor nodes of the node. In addition, in the waiting phase, the nodes that carry a copy of the message are no longer waiting for the destination node and then delivering it directly. When nodes move in the process of encountering nodes that have greater probability of meeting with the destination node and smaller conditional contact intervals, the message copy will be forwarded to the node. The simulation results show that the improved routing algorithm has good performance in the success rate of message delivery, the average end to end delay, the network overhead and so on.
【學(xué)位授予單位】：電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TN929.5
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本文編號(hào)：1340048